Posted
by
Soulskill
on Friday July 31, 2009 @11:09PM
from the tried-everything-else dept.

katarn writes "General Fusion is a startup proposing they can create commercially viable fusion using acoustic shock waves, triggered by 220 precisely controlled pneumatic pistons. Their approach is based on a US Naval research concept called 'Linus' and old research done by General Atomics. They feel we now have the high-speed, digital processing capable of pulling off this feat, where decades ago the technology was not available. I think we can hold off on the 'vaporware' claims for a bit; everyone is aware of the horrible track record for turning fusion concepts into reality, but they don't claim to be the first with the idea or that there are not substantial challenges in the way. If nothing else, it is a fascinating concept."
Los Alamos National Laboratory has further details on this type of fusion, and longtime LANL researcher Ronald Kirkpatrick did an external assessment (PDF) of General Fusion's plans. Popular Science had a lengthy story about the company a while back. The reason they're back in the headlines now is that they've secured enough funding to begin work on a prototype reactor.

"Somebody described it as a thermonuclear diesel engine," Laberge says, perhaps undervaluing a potentially awesome marketing phrase. "We compress the fuel. It burns."

Rudolf Christian Karl Diesel would be proud! Really, what human with a Y chomosome wouldn't want to drive a big-rig with a freakin Thermonuclear Diesel Engine!? Steampunk, but with 3 orders of magnitude more available enthalpy! We're talkin locomotive to the stars, here!

I instantly thought steampunk too. Now you've got an image in my head of a master engineer with steampunk goggles pulling a lever, custom brass components whirring and chugging, and then a train silently roaring across the frame, occluding the stars, and disappearing in the distance toward Jupiter.

So a project code named "linus' makes the tag sharks think we are all idiots and can't read the article? This has a chance of working. It might be an off chance but anytime Los Alamos is involved you had damn well better put some stock in it. On second thought... Linus made linux, and this was code named 'Linus". Therefore we can now call it Fusex.

Only in the vaguest sense. The secondary stage in a thermonuclear bomb is triggered by a fission primary, however the secondary stage in a thermonuclear bomb is not a purely fusion weapon. It's a multilayer sandwich. The secondary starts off with another fission reaction (the plutonium spark-plug), which helps trigger the fusion reaction (lithium deuteride), which in turn boosts the ongoing fission reaction in the spark plug, which in turn boosts the ongoing fusion reaction. Finally it produces a neutron flux which detonates and consumes the secondary casing (depleted uranium, U-238). Most of the energy in a thermonuclear bomb comes from the fission of the depleted uranium protective casing. Thermonuclear bombs do fission 'better' than purely fission bombs.
For the record, this was discovered accidentally when Castle Bravo was a much bigger bang than the designers expected.

Hah, yeah right! You're going to have to make up some more believable sounding sciencey words before we fall for THAT one. Why don't you just go reroute the flux capacitor through the deflector to invert a tachyon pulse while you're at it?
Comedians...

which in turn boosts the ongoing fission reaction in the spark plug, which in turn boosts the ongoing fusion reaction. Finally it produces a neutron flux which detonates and consumes the secondary casing (depleted uranium, U-238).

Dear sir
I would like to personally thank you for helping us the great people of North Korea to finalize our procedures.
Kim Jong-il

The huge yield of Castle Bravo was more due to the unexpected reactions with lithium-7. It wasn't expected to react, but it does capture neutrons, then decays into tritium + a neutron. The tritium quickly fuses with deuterium and releases yet more neutrons. Much of the yield was from the uranium casing, but the reason was the extra high energy neutron flux from the lithium-7. And the secondary in a TU design has the fusion squeezed from both the spark plug detonation (plus a lot of neutrons) and the ablative pressure, on the tamper, from the primary. I'm going to guess that they used a larger amount of the lithium-deuteride because it was only partially enriched. Which meant a lots of unexpected extra energy and neutrons from the lithium-7.

Mr. Burns: [over the hotline] Oh, meltdown. It's one of these annoying buzzwords. We prefer to call it an unrequested fission surplus.

There's been some modest interest in actively stabilized fusion for a while, but this is the first mechanical scheme.

The basic problem with fusion reactors is that the plasmas aren't stable. Most work to date involves trying to come up with some geometry that produces an inherently stable plasma. So far, nothing works, although some geometries almost work. But it's not that hard to build a small machine that has an unstable plasma.
The original Stellerator, in 1951, did that.

The instabilities occur on the order of milliseconds, not microseconds or nanoseconds. That's slow enough that some kind of active stabilization scheme to nudge the instabilities back in line might work. Something with a large number of sensors and actuators.
But I'd been expecting electrostatic deflection plates or magnets, not physical pistons.

Not a ground to orbit engine, the assembly would be too heavy for the max thrust of current non-chemical fueled engines. But once in orbit the energy generated could run a VASIMR, conventional ion or water/steam based thruster quite well. With something like that Mars would be less than 6 month round trip, the outer planets and more importantly asteroids would be within practical reach. This kind of engine could be used to bring an asteroid into Earth orbit for mining or divert a rock on an impact trajectory.

The more I think about it the more I think this idea is just crazy enough to work.

You could attach four smart mechanical arms to someone's brain stem (with an inhibitor chip of course). Those extra arms could make the millisecond adjustments to keep the instabilities in check. I have to admit this sounds familiar...

Or just have a most excellent project welder bring home the core component and play some music [imdb.com] to figure out the secret acoustical sound. The story doesn't mention how upset some organiszations will be, willing to blow up lots of things to keep this technology secret.

So in order to maintain the fusion reaction they're going to physically shove the plasma into alignment whenever it develops an instability? Are you saying that Spider-Man 2 was actually correct about its physics? I'm not sure if this means i should be looking forward to flying cars in the near future or watching out for an attack by super villains.

They're not going to stabilize the plasma at all, if I understand this right (IANANP). It's a pulse fusion model: put your hydrogen in the middle, surround with a working fluid that they refer to as "liquid metal" (made of lead + lithium), fire off pistons to make a pressure wave in the liquid metal and make a burst of fusion in the middle, generating heat. This makes the molten lead even hotter, and it's circulated through a heat exchanger. The cool part, I thought, was that the lead also absorbs radiation so the casing and equipment doesn't fall apart after a few months because the neutron flux made it brittle. That's a neat trick.

One neat thing that they didn't mention: having lithium exposed to a high radiation flux will breed more tritium

And having lead exposed to a high neutron flux will breed all kinds of long-lived nuclear waste, which has generally been one of the advantages of fusion (looking past the whole "doesn't actually exist" thing.) That said, the waste will should still be more managable than fission products, and the production of long-lived actinides will be small, if non-negligible.

Yeah the lead will absorb radiation, but when it absorbs those fast neutrons
from the fusion reaction, it will split like uranium does in fission. Except some
very nasty radioactive daughter products. With the lead, this is not be clean
energy, it will rather dirty indeed.

I've been waiting for this (acoustically contained/pumped fusion). Its just one more way to add energy, create confinement and maintain resonance. And whats with Sonoluminescence [wikipedia.org] anyways? The whole tokamak thing seemed a little ill conceived when I heard how difficult it is to keep the vacuum from being poisoned and energy from leaking away from the desired chain reaction.

Uhhhh, what are you talking about? The plasma parameters are not by any means, in so far as I can see, actively controlled in any way in this scheme. Their plan is to launch two colliding toroidal vortex rings of hot plasma into the vorticular void of a large sphere or rapidly spinning molten LiPb metal. Then, using pistons, they launch an imploding spherically symmetric shockwave into the metal to converge upon the merged spheromaks at the center of the setup. The TOTAL confinement time looks like it'll be measured in microseconds at most on this thing, no way is there time for active control of the plasma during a shot like that.

As fusion schemes go, I am obligated to express my opinion that this one is way fucking wacky, however, it is significantly less wacky than a lot of other ideas out there (polywell, I'm looking at you) and it does not appear to have any immediate show stoppers associated with it which would allow me to dismiss it out of hand. I am not a physicist, but I did just get home from my job working on one of the nation's largest conventional (laser driven) inertial confinement fusion reactors and I have a very deep enthusiast's interest on these matters. On the laser fusion device that I work on, we have recently begun shooting MTF targets (we call it MIF or magneto-inertial fusion though) on our system as well [rochester.edu], and the results are quite interesting. We use a centimeter scale, single loop Helmholtz coil setup with a conventionally laser-driven fusion microcapsule sitting at the center of the coils. The laser fires, compressing the D-T fuel to tremendous pressure and temperature (higher than in the sun's core) and just before the exact moment of maximum compression and fusion burn (bang time) the Helmholtz coils are fired with power from a couple hundred Joule capacitor bank, thereby producing a huge magnetic field in the compressed target capsule and hopefully increasing the plasma confinement time from a mere few picoseconds to several times longer (the Larmor radius of charged particles in a magnetic field of the intensity we produce is on the order of the size of the compressed capsule, it effectively suppresses electron thermal conductivity and confines the hot plasma within itself). Proton deflectrometry has been successfully used to validate the expected ~.2 megagauss magnetic fields in our setups. The work ahead of the guys with this piston driven shockwave idea is enormous, but the field of plasma and fusion physics is still rich with exciting discovery. I wish these gentlemen the very best of luck.

I won't sugarcoat my thoughts on that one, I'd say it's nothing more than a fraud. The lowest of the low, vastly kookier than even Bussard's Polywell. I have followed discussions about Eric Lerner and focus fusion VERY closely on the wikipedia pages and I have little to no respect for that man's ideas about fusion or his tactics of argument. He does not have a PhD and he is not a physicist. His ideas about the "electric universe" are idiotic pseudoscience. I will refer you specifically to the plasma physicist Art Carlson's highly thoughtful and reasonable objections to unconventional fusion schemes in general on this issue, and his objections to focus fusion in particular (all on the wiki pages). His credentials and intellectual honesty in these debates seem, to me anyway, to be impeccable.

Robert Bussard can be forgiven for his sin of the polywell. He was a really good scientist who achieved some truly admirable things in his career, but at the end I think he realized that he was getting old and would never live to see his dream of fusion power come true, and he started making wacky claims when things became desperate (like extrapolating his supposed observation of three -count em- THREE fusion neutrons from one of his setups to commercial scale power cost estimates, that's just pain nutty). It's unfortunate but entirely forgivable. Art Carlson's criticism of the polywell device as a non-starter due to its being classified as a reactor whose plasma is in thermodynamic disequilibrium (Todd Rider's MIT thesis on this showed that the bremsstrahlung losses are insurmountable) are highly convincing, and the waffling and flouncing about that the polywell supporters do in the face of these criticisms seem highly dubious.

Personally I'm holding back on putting the 100k down on the Tesla 2020 with 220 cylinder fusion engine. But I wouldn't claim a University of Wikipedia education to condemn a new idea; I wouldn't want to make a statement on the workability without a Ph.D. in high energy physics myself. Compared to the billions spent on the confined plasma schemes, pulse set-ups are cheap to implement and see if you get excess neutrons or not. The one thing we learned from the cold fusion disaster, the claims don't last long

Eh what? Please excuse my ignorance, as I have only been following this casually, but. . ..

I thought it had been long shown that Todd Rider's paper doesn't address (i.e. is not applicable to) the Polywell device.

I seems to me that most critics of Polywell go off track when they start describing the ions in the reactor as a hot plasma (as if it were a kind of tokamak), when it would be more apt to view them as a converging particle beam. The type of directed (as opposed to random) kinetic energy those par

Polywell more wacky than this? There are a number of things I can't see them getting right with this piston concept any time soon. Personally, I don't think they can make a uniform shockwave using pistons, but we'll see I guess. The plasma vortex rings sounds interesting. I guess my primary question would be using the lead lithium blanket next to the plasma. Invariably, you'll have some vapor in the plasma region, and these higher Z atoms should wreck havoc with Bremsstrahlung radiation. The polywell alread

I am in agreement with most of your thoughts except the polywell neutron claim. Have they published with statistically significant neutron yields? I'd like to read it if so. The General Fusion guys will definitely have to deal with severe Richtmyer-Meshkov instability when the shockwave breaks out of the molten metal into the plasma at the center, and then Rayleigh-Taylor instability when the plasma itself if compressed. Question is, how uniform of a shockwave will they need? Who knows. The CDX-U and LTX to

The TOTAL confinement time looks like it'll be measured in microseconds at most on this thing, no way is there time for active control of the plasma during a shot like that.

I see that. So what do they want all the compute power for? I'd assumed I was reading an oversimplified version, and all the compute power was to actively stabilize something. If they just need a simultaneous push, they don't need compute power. I'm missing something.

There's other work like that, and hope that one of the designs that's almost stable might be nudged into stability with active control.

But there are practical issues to deal with, assuming that they even get it to be somewhat stable. Exactly how long can they maintain it before one of the pistons fails? What happens if one fails? How do they capture and utilize the energy created?(big one here) How much heat eventually will end up being radiated back into the machine itself and the surrounding area?(ca

here's work on active stabilization. See "Active-Feedback Control of the Magnetic Boundary for Magnetohydrodynamic Stabilization of a Fusion Plasma" [aip.org]. That's a 2006 paper on a scheme involving 192 active feedback coils to stabilize a plasma. There's other work like that, and hope that one of the designs that's almost stable might be nudged into stability with active control.

Yes but that work was done on the reverse field pinch device called RFX-mod ( http://www.igi.cnr.it/rfxmod2009/ [igi.cnr.it] ). It's a tokamak-like magnetic confinement device so it probably has shot times measured in the multi-second range. Plenty of time for active stabilization but way different from this new MTF approach.

Your laser compressed, ignited and magnetic flux stabilized fusion scheme looks more reasonable and promising than this (TFA) mechanical molten lead and piston driven foolishness, hopefully you guys will be able to produce some real word energy producing setup soon.

But it's not that hard to build a small machine that has an unstable plasma.The original Stellerator, in 1951, did that.

Uh, the advantage of a Stellarator is that it's a stable configuration... relatively speaking.

And indeed it is not difficult to build a machine with an unstable plasma. The history of magnetic confinement fusion research is "oh I've got this great idea for a stable plasma configuration" followed by "we built it and found out that it's not stable enough."

Perhaps if the D-T reactor does really well they can redesign it to handle a fuel composed of hydrogen ions (protons, in other words) and Boron-11 ions. The products of this reaction are helium-4 ions, which are not radioactive and do not induce radioactivity in their containment vessel if they are captured electrically. Electrical capture also avoids the losses associated with converting heat to electricity.

I really hope General Fusion gets this to work, but if I had any money, my money would be on EMC2 Corp, which is working on inertial electrostatic fusion. This [blogspot.com] or this [emc2fusion.org] should get you started on a search for more information.

If you read the site, you'd see one of the tricks they have up their sleeve to deal with the radioactivity problem: they surround the actual fusion process with a working fluid of molten lead (and lithium) which not only transmits the shockwave from the pistons, but also absorbs neutrons. If the reactor does well, they shouldn't have to change the fuel at all.

My guess is that 204Pb will absorb a neutron and transmute to 205Pb, which decays to a stable isotope of thallium, and 208Pb will transmute to 209Pb, which decays to nearly stable bismuth. The other lead isotopes look like they should just become heavier stable lead isotopes. I don't see any obvious waste problems here.

It's the same idea, essentially -- a shock focused from all directions onto a point in the middle.

Ultrasound pumped into a resonant cavity is just a different way of starting the shock (and you get many shocks per second with a higher efficiency -- whether this is a good thing or a bad thing depends on what you're doing)

There's a reason fifties novels sound like that. It has to do with art imitating life, not the other way around. General Atomics was real. So were General Dynamics and General Electric. So were companies like North American Aviation and The Aerospace Corporation. Some of them even still exist.

I've lived in the area for a long time, and never heard a good story about the VSE (RIP 1999), it's remains, but not the lingering stench, since composted into the CDNX.

Wikipedia just provided me with a funny story about the VSE I didn't know, but find all too typical.

The history of the exchange's index provides a standard case example of large errors arising from seemingly innocuous floating point calculations. The index was initialized at 1000 and subsequently updated and truncated to three decimal places on each trade. The accumulated truncations led to an erroneous loss of around 20 points per day. Over the weekend of November 25-28 1983, the error was corrected, raising the value of the index from its Friday closing figure of 524.811 to 1098.892

Are these the same people who are proposing to solve the fusion problem with 220 synchronized penises? Good god, I hope not.

For the record, here's what $500m typically buys you in British Columbia.

Maybe we should just move all companies and their fusion experiments to one, single 'fusion science park', with each building next to each other in a ring. We then use large bulldozers to smash all the buildings towards the centre at the same time and see what happens?

To expand on that point, because it's inexpensive, it uses common materials, and it scales.
The problem of "I have an object here that produces lots of heat energy, I'd like to convert that heat to useful work, please"
is harder than it sounds.

Why flamebait? You are correct. I would also like to add the US military budget...

The US has the means to fund this research. It has chosen not to do so.

Ummmm. Just want to note that historically speaking the Department of Energy has funded nearly as much in research dollars as the Department of Defense, and that the amount of money spent on (failed) attempts at fusion is not insignificant by any means. You don't see all that much money going to fusion research these days because not many people have come up with NEW ideas that have any sort of solid backing in theoretical physics. In fact, most physicists would argue that its STILL way, way, too easy to get research dollars for purely ridiculous ideas of generating fusion.
I will also add that there are still relatively substantial funds going into hot fusion and attempts to improve the energy balance from there.
Finally, this whole point is irrelevant to the parent -- large government grants for basic research usually don't go to startups simply because there's no track record of research success etc. Instead they typically go to universities and other established research centers -- and I assure you that the average university has plenty of grants awarded for stuff pretty far out there. On the other hand the Small Business Initative Research grants from DoD etc. are actually a fairly impressive program. While there is definitely no such thing as spending too much money on research, so far as I am aware the US is still on the leader board in terms of research spending.

I'm a bit curious as to why we haven't heard more about a fusion reactor based around Sandia's Z-Pinch.

AFAIK, the Z Machine has experimental results showing that efficient fusion could be achieved using a similar technique. Why aren't we pouring all of our resources in this direction, given that we've got evidence showing that it will work? Tokamak designs seem to have a tendency to be outrageously large, expensive, and unproven.

As someone who works for a startup, I cannot empathize how WRONG you are. Almost every aspect of what we do to bring our particular product to market is new and needs to be thoughtfully researched and developed. It isn't easy but the potential rewards make it worthwhile. We spend a lot of time 'proving' our ideas with prototypes to provide proof that we know what we are doing and that the risk for investors is reduced.

Startups, by their very nature, do not succeed on a bet that the technology will be invented. Venture capitalists do not support fairytale wishes.

So very, very ill-informed. Betting on needed technology being invented is a risk and the very thing venture capitalists do is to take great risks expecting to reap in big profits. Profits that cover more than all their other risky investments that fail since they expect most to fail. That is the definition of venture capitalist.

One counterexample to your point is worth mentioning: Startups driven by ex-academics. There are case studies of successful ventures where researchers came out of the university and into the private sector to apply research to commercial problems. They are niche, but perhaps that's how you could clarify your assertion - by also mentioned niche solutions based on solid research.

Well, the good news in their case is that they're not inventing most of the components so much as engineering them... steam pistons are not high-tech, and it's only a matter of adapting them to their system's needs.

Also, I used to work with one of their principles - Doug Richardson (he was my boss at the time). He's just about the right mix of weird, brilliant, and stubborn to make this work. At least I can assure you they're not some crackpot garage operation - they have a solid basis for their design an

The vast majority of fusion research funds from US government flow through the Department of Energy. The senior guys at the DoE have a few pet approaches to fusion, and 99.9% of the funding goes into those. Innovative, small scale, low cost approaches like this, or IEC polywell fusion are left begging to the Navy for funds, but the Navy has far less money to spend on nuclear research than the DoE.

The US govt does an incredible amount of RD that they never follow up on i.e. it is more Rd, rather than RD. The reason is money. Take the example of TransHab. Thankfully, Bigelow has been pursuing it. If we are VERY lucky, the Augustine commission will recommend that we buy one or two and attack to the ISS to help him alone.

And this particular example, the Navy does a LOT of nuke funding. Have to. If we can create a reactor that is much smaller in size, it will change a lot of things for US. DARPA also h

The website looks just like a startup's website to me. The copy has been written by the MD (or the MD's marketing friend) and the layout is exactly what you get from someone technical who can do html but does their best to minimise their contact with it. The fonts in particular are using the "verdana, arial, helvetica, sans-serif" list straight out of "the manual" and the layout is a dead simple table layout copied from before everyone got conned into trying to do all the layout using CSS.